The present invention relates to semiconductor technologies, and more particularly to photolithography techniques for the fabrication of semiconductor devices.
In the field of semiconductor technology, the positive tone develop (PTD) technology uses TMAH (Tetramethylammonium hydroxide) to dissolve photoresist in the exposed areas. In contrast, in negative tone develop (NTD) technology, an organic solvent is used to dissolve away the photoresist in regions that have not been exposed. Negative tone develop (NTD) technology can improve small pitch resolution and has relatively broad application prospects.
However, the inventor has identified certain limitations in conventional negative tone develop (NTD) technology as explained below. FIGS. 1A to 1C are cross-sectional view diagrams illustrating a conventional lithographic method, which includes the following steps:    Step E1: On a film 100 that is to be etched, sequentially form the following layers: a bottom anti-reflective coating layer (BARC) 101, a positive resist layer 102, and a water-resistant top coating (TC) layer 103, as shown in FIG. 1A;    Step E2: Using a mask plate 600 to perform an exposure process on positive photoresist layer 102, forming exposed areas 10201 and non-exposed areas 10202, as shown in FIG. 1B;    Step E3: Perform a negative development treatment to form a patterned photoresist 1021 to be used as a mask, as shown in FIG. 1C.
Patterned photoresist 1021 formed as described above will often exhibit a T-shaped profile, i.e., the top portion of the patterned photoresist is wider than the bottom portion. The presence of the T-top defects can reduce the ability of negative development technology (NTD) to achieve a small pitch. Various methods have been proposed to solve the T-top defect issue, such as changing the solvent DEV, improved optical contrast (NILS), changing the negative photoresist component, and the like. However, these conventional solutions are not satisfactory. Therefore, in order to solve this technical problem, an improved lithographic method is needed.